The Bock Casemates

The Bock Casemates are the spectacular heart of Luxembourg City's mighty former fortress and part of its UNESCO World Heritage Site. Carved into the sheer Bock promontory, the very cliff where Count Siegfried founded Luxembourg in 963, this astonishing labyrinth of tunnels, galleries and cannon chambers riddles the rock over several levels. Once part of a 23-kilometre underground network capable of sheltering thousands of soldiers, horses and workshops, the surviving passages can be explored today, offering dramatic openings and views out over the gorges below.

What you actually see

• The rock-cut galleries - the labyrinth of tunnels through the cliff.
• The cannon chambers - the old artillery openings in the rock.
• The gorge views - the dramatic windows over the valleys.
• The Bock promontory - the birthplace of the city above.

When to go

The casemates are generally open from spring to autumn; go on a fine day to enjoy the dramatic openings and views over the gorges, and wear sturdy shoes and a layer, as the passages are uneven, steep in places and cool underground. They combine naturally with the clifftop old-town walks above.

Honest expectations

The tunnels involve steep, uneven steps and low, narrow passages that can be tight, damp and dimly lit, so they are less suited to those with limited mobility or claustrophobia, and much of the original vast network was demolished. The surviving warren, though, is genuinely atmospheric and remarkable, a fascinating plunge into the rock that made Luxembourg one of Europe's great fortresses.

Nearby

The old town, the Corniche rampart walk and the Grund are just above.